Applicator comprising a sealing membrane

ABSTRACT

The disclosure concerns an applicator (e.g. print head) for applying a coating agent (e.g. paint) to a component (e.g. motor vehicle body component), having a nozzle chamber with a plurality of nozzles for dispensing the coating agent in the form of continuous jets or droplets, the coating agent flowing during operation through the nozzle chamber to the nozzles so that the nozzle chamber is filled with the coating agent during operation. The print head further comprises a plurality of slidable valve needles associated with the individual nozzles and selectively opening or closing the respective nozzle depending on the position of the valve needles. Furthermore, the print head according to the disclosure contains an actuator chamber for receiving actuators for displacing the valve needles. In addition, the applicator according to the disclosure has a sealing element which fluidically separates the actuator chamber from the nozzle chamber in order to avoid contamination of the actuator chamber with the coating agent in the nozzle chamber. The disclosure provides that the sealing element is designed such that the individual valve needles can be displaced independently of one another without a displacement of one of the valve needles impairing the opening and closing of the nozzles at the adjacent valve needle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to, U.S.patent application Ser. No. 16/649,226, filed on Mar. 20, 2020, which isa national stage of, and claims priority to, Patent Cooperation TreatyApplication No. PCT/EP2018/055578, filed on Mar. 7, 2018, whichapplication claims priority to German Application No. DE 10 2017 122488.2, filed on Sep. 27, 2017, which applications are herebyincorporated herein by reference in their entireties.

FIELD

The disclosure concerns an applicator (e.g. a print head) for theapplication of a coating agent (e.g. paint) to a component (e.g. carbody component).

BACKGROUND

The state of the art (e.g. U.S. 9,108,424 B2) includes so-calleddrop-on-demand print heads, which emit a droplet jet or a continuouscoating agent jet and whose operating principle is based on the use ofelectric valves. A magnetically driven plunger/armature is guided in acoil. If the plunger of the electromagnetic actuator and the sealingelement, which closes the valve seat, is a component, it is referred toin the following as a valve plunger. Depending on the current supply tothe coil, the valve plunger is shifted and a nozzle is either releasedor closed. Such print heads are also described in WO 2012/058373 A2.These print heads also work with valve plungers which are moved byelectric coils, whereby the valve plungers run in a guide tube (coilinner tube) in the coil.

A problem with the known print heads is the fact that the actuators usedto move the valve plungers are exposed to the coating agent duringoperation. This is initially not a problem if the coating agent is notto be changed, the coating agent is of low viscosity and no majorpressures occur and the heating of the coil inner tube by theelectrically energized coil does not lead to partial drying of thecoating agent. However, coating agents with a higher viscosity (e.g.more than 80 mPa·s at a shear rate of 1,000 s⁻¹) are often used in thepainting of vehicle bodies. In addition, the paintwork of vehicle bodiesoften involves a color change. Furthermore, the known print heads do notmeet the requirements for painting vehicle bodies, as the print headsshould be as free of undercutting, dead space and flow optimized aspossible. As a result, the known print heads are not or not optimallysuitable for the painting of vehicle bodies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a schematic representation of a print head according tothe disclosure with all nozzles closed,

FIG. 1B the schematic representation from FIG. 1A, where a single nozzleis open,

FIG. 2 shows a schematic representation of the sealing membrane of aprint head according to the disclosure with a hole for a valve needle,

FIG. 3 is a variation of FIG. 2, where the valve needle and nozzleclosure tip are separated and screwed together,

FIG. 4 is a variation of FIG. 3, wherein the nozzle closure tip isformed on the sealing membrane,

FIG. 5 a schematic representation of a sealing membrane of a print headaccording to the disclosure with knobs as three-dimensional structure,

FIG. 6 shows a schematic view of a sealing membrane with athree-dimensional structure,

FIG. 7 is a variation of FIG. 6,

FIG. 8A a variation of FIG. 6,

FIG. 8B shows a section along the section line A-A in FIG. 8A,

FIG. 8C a section view along the section line B-B in FIG. 8A,

FIG. 9A is a variation of FIG. 6,

FIG. 9B a section view along the section line A-A in FIG. 9A,

FIG. 9C a section view along the section line B-B in FIG. 9A,

FIG. 10A a variation of FIG. 6,

FIG. 10B a section view along the section line C-C in FIG. 10A,

FIG. 10C a section view along the section line D-D in FIG. 10A,

FIG. 10D a section view along the section line A-A in FIG. 10A,

FIG. 10E a section view along the section line B-B in FIG. 10A,

FIG. 11A a variation of FIG. 10A,

FIG. 11B a section view along the section line C-C in FIG. 11A,

FIG. 11C a section view along the section line D-D in FIG. 11A,

FIG. 11D a section view along the section line A-A in FIG. 11A,

FIG. 11E a section view along the section line B-B in FIG. 11A,

FIG. 12 an enlarged view of a section of FIG. 11A with dimensions toexplain the proportions,

FIG. 13 a schematic representation of a sealing membrane with a sealingcollar,

FIG. 14 a variation of FIG. 13,

FIG. 15 a variation of FIG. 13,

FIG. 16 a variation of FIG. 13,

FIG. 17 shows a schematic representation of an application systemconforming to the disclosure with an applicator conforming to thedisclosure with two membranes,

FIG. 18A a schematic representation of the applicator with the twomembranes, and

FIG. 18B a variation of FIG. 18A with different pressure ratios.

DETAILED DESCRIPTION

The disclosure is therefore based on the task of creating acorrespondingly improved applicator.

The print head according to the disclosure is generally suitable for theapplication of a coating agent. The disclosure is therefore not limitedto a specific coating agent with regard to the coating agent to beapplied. Preferably, however, the print head is designed for theapplication of a paint.

It should also be noted that the print head according to the disclosureis generally suitable for applying the coating to a particularcomponent. With regard to the type of component to be coated, thedisclosure is also not limited. Preferably, however, the print headaccording to the disclosure is designed to apply a coating agent (e.g.paint) to a motor vehicle body component or an add-on part of a motorvehicle body component.

The print head according to the disclosure initially has a nozzlechamber with several nozzles, whereby during operation the nozzlesrelease the coating agent in the form of a continuous jet or in the formof a droplet jet. The print head according to the disclosure thusdiffers from atomizers (e.g. rotary atomizers, air atomizers, etc.),which do not emit a spatially limited jet of the coating agent, but aspray of the coating agent. During operation of the print head accordingto the disclosure, the coating agent to be applied flows through thenozzle chamber to the nozzles, so that the nozzle chamber is filled withthe coating agent during operation.

In addition, the print head according to the disclosure has preferablyseveral displaceable plungers which are assigned to the individualnozzles and optionally open or close the respective nozzle depending onthe position of the plunger.

In a variant of the disclosure, the plungers/armatures also form thevalve needles and can optionally open or close a valve seat depending ontheir position.

In another variant of the disclosure, on the other hand, the slidingplungers/armatures are separated from the actual valve needles and onlyact on the valve needles mechanically connected via a so-called hammer,which then open or close a valve seat depending on their position.

In the following only valve needles are mentioned, this can be a valveneedle (actuator plunger/armature connected to the valve needle via ahammer) as well as a valve plunger (actuator plunger/armature is thesame component as the sealing element that closes the valve seat).

It should also be mentioned that the valve seat does not have to belocated directly at the nozzle. It is also possible that the valve seatis located in front of the nozzle and connected to the nozzle via apipe.

In addition, the print head according to the disclosure has an actuatorchamber in which the actuators for moving the individual valve needlesare arranged in accordance with the known print heads. For example, theactuators can be electromagnetic actuators with solenoid coils, as isthe case with the known print heads described above. However, thedisclosure is not limited to magnetic actuators with regard to the typeof actuators, but can also be realized with other types of actuators,such as piezoelectric actuators or pneumatic actuators. Preferably,however, the actuators are electrically controllable, so that they areelectromechanical actuators.

The print head according to the disclosure may additionally provide asealing element (e.g. in the form of a continuously closed membrane or amembrane with ducts for valve needles), which fluidically separates theactuator chamber from the nozzle chamber in order to avoid contaminationof the actuator chamber with the coating agent in the nozzle chamber.

In the following, the term sealing membrane is used instead of the termsealing element. However, the sealing element does not necessarily haveto be a sealing membrane. The sealing membrane thus prevents the coatingagent in the nozzle chamber from reaching the actuator chamber duringoperation and also when switched off.

In a preferred embodiment of the disclosure, the sealing membrane iscontinuous and separates the actuator chamber from the nozzle chamberfor all or at least a large part of the nozzles. This means that anindividual sealing membrane is not provided for each nozzle with theassociated actuator. Rather, all nozzles with the associated actuatorshave a common sealing membrane which separates the common actuatorchamber from the common nozzle chamber.

Preferably, the continuous sealing membrane is designed in such a waythat the individual valve needles can be displaced independently of eachother without a displacement of one of the valve needles impairing theopening and closing of the nozzles at the adjacent valve needle. Duringoperation of the print head according to the disclosure, it is desirablethat the individual nozzles can be opened or closed individually.However, the continuous sealing membrane can lead to a mechanicalinteraction between the adjacent valve needles. For example,displacement of one of the valve needles may lead to a correspondingdeflection of the sealing membrane, whereby this deflection of thesealing membrane due to the elasticity of the sealing membrane wouldthen also exert a corresponding deflection force on the adjacent valveneedles, which would not be desirable. The disclosure therefore providesfor this undesirable mechanical interaction between the adjacent valveneedles to be reduced due to the common sealing membrane at least tosuch an extent that the adjacent valve needles can open or close theassociated nozzles independently of each other without mutualinterference.

This is preferably achieved by the fact that the common sealing membranehas a three-dimensional structure which prevents a displacement of oneof the valve needles from affecting the opening and closing of thenozzles of the adjacent valve needles.

In a variant of the disclosure, this three-dimensional structure of thesealing membrane is located only on the side of the actuator chamber. Inanother variant of the disclosure, however, the three-dimensionalstructure of the sealing membrane is only on the side of the nozzlechamber. Finally, it is also possible that the three-dimensionalstructure of the sealing membrane is located on both sides of thesealing membrane, i.e. both on the side of the nozzle chamber and on theside of the actuator chamber.

The three-dimensional structure can have various structural elements,such as at least a cube, a cuboid, a tetrahedron, a prism, a rib, arecess or, in general, an elevation. These different types of structuralelements can also be combined in the three-dimensional structure.

It should also be mentioned that the structural elements of thethree-dimensional structure can be square, rectangular, triangular,parallelogram-shaped or round-arch-shaped in a top view of the sealingmembrane, to name just a few examples.

In the preferred embodiment of the disclosure, the sealing membrane hasat least one row of holes assigned to the individual valve needles. Therow of holes is preferably straight (linear), but it is also possiblethat the row of holes in the sealing membrane is curved, for examplearc-shaped.

With regard to the position and orientation and dimension of theindividual structural elements of the three-dimensional structure inrelation to the row of holes, there are various possibilities within thescope of the disclosure.

Preferably, the individual structural elements of the three-dimensionalstructure are each elongated and aligned with their longitudinal axisrelative to the row of holes in a certain way. For example, theindividual structural elements can be aligned parallel to the row ofholes. Alternatively, it is also possible that the individual structuralelements are aligned transversely to the row of holes, especially atright angles. It is also possible for the individual structural elementsof the three-dimensional structure to be aligned obliquely with respectto the row of holes.

The disclosure also offers various possibilities with regard to theposition of the individual structural elements in relation to the row ofholes. For example, the individual structural elements can be arrangedin at least one row parallel to the row of holes. One possibility forthis is that the individual structural elements are arranged exactly inthe row of holes between the adjacent holes. Alternatively, it is alsopossible for the individual structural elements to be laterally spacedand arranged parallel to the row of holes, in particular on both sidesof the row of holes in a line with one of the holes in each case. Thestructural elements and the individual holes can thus be aligned in sucha way that each hole is adjacent to one structural element on both sidesof the row of holes.

The disclosure also offers various possibilities with regard to thedimensional relationships of the individual structural elements inrelation to the row of holes.

Also with regard to the height of the individual structural elements,there are various possibilities within the scope of the disclosure. Itshould be mentioned here that the height of the structural elements ismeasured at right angles to the base area of the sealing membrane. Forexample, the height of the structural elements can essentially beconstant within the individual structural elements. Alternatively, it ispossible that the height of the individual structural elements varieswithin the structural elements. For example, the height of theindividual structural elements can increase or decrease towards theadjacent hole. There is also the possibility that the height of theindividual structural elements increases or decreases towards the row ofholes, i.e. from the outside to the inside.

Within the scope of the disclosure, it is also possible that the sealingmembrane around the individual holes has a annular bulge. This annularbulge is also a possible form of a structural element of thethree-dimensional structure of the sealing membrane. Here, too, it ispossible that the annular bulge is arranged only on the side of theactuator chamber, only on the side of the nozzle chamber or on bothsides.

It should also be mentioned that the sealing membrane may have a sealingcollar at the peripheral edge of each hole to seal the hole from thevalve needle. The sealing collar can either protrude only towards theactuator chamber, only towards the nozzle chamber or protrude on bothsides. With regard to the sealing collar, it should also be mentionedthat the cross-section of the sealing collar can, for example, betriangular. The ratio of the diameter of the valve needle to the lengthof the sealing collar can be ≥0.5, ≥0.7, >1, ≥1.5 or even ≥2 the case ofthe disclosure variant with several sealing membranes described indetail later, all sealing membranes can have such a sealing collar.

In an embodiment of the disclosure the individual valve needles are heldin the holes of the sealing membrane by a press connection with acertain contact force.

In a variant of the disclosure, this contact force is dimensioned insuch a way that the valve needles are axially fixed in the holes of thesealing membrane and cannot slide axially in the holes of the sealingmembrane. As a result, a displacement of one of the valve needles leadsto a corresponding deflection of the sealing membrane.

In another variant of the disclosure, on the other hand, this contactforce is dimensioned in such a way that the valve needles canessentially slide freely axially in the holes of the sealing membrane.This means that a displacement of one of the valve needles does not leadto a corresponding deflection of the sealing membrane.

A further variant of this embodiment of the disclosure, on the otherhand, provides that the valve needles in the holes of the sealingmembrane can partly slide freely and are partly axially fixed. When oneof the valve needles is displaced, this valve needle first takes thesealing membrane axially with it, which leads to a corresponding axialdeflection of the sealing membrane. As the valve needle continues tomove, the elasticity of the sealing membrane causes it to offer greaterresistance, which leads to the valve needle slipping through as thevalve needle moves.

It should also be mentioned that the nozzle chamber can have arelatively small volume, which can be a maximum of 100 mL, 50 mL, 10 mL,5 mL or even a maximum of 1 mL, for example.

With regard to the holes in the sealing membrane, it should also benoted that its internal diameter is preferably smaller than the externaldiameter of the valve needles in order to ensure a seal. For example,the inner diameter of the holes may be 0.1 mm, 0.2 mm, 0.3 mm or 0.4 mmsmaller than the outer diameter of the valve needles. However, it isalso possible that the inner diameter of the holes in the sealingmembrane may be 10%-50% or 20% 40% smaller than the outer diameter ofthe valve needles.

In addition to the sealing membrane itself, it should also be mentionedthat it can be made of ceramic, metal or plastic, for example. Examplesof plastics are polyethylene (PE), polypropylene (PP), polyoxymethylene(POM), thermoplastic polyurethane (PU), thermoplastic elastomer,polytetrafluorethylene (PTFE), polyketone (PK) or polyamide (PA), toname just a few examples.

It should also be mentioned that the valve needles and the holes in thesealing membrane should be aligned as precisely as possible relative toeach other. There is therefore only a very small radial deviationbetween the centre of the holes on the one hand and the longitudinalaxis of the associated valve needles, which is preferably smaller than0.2 mm, 0.1 mm or even smaller than 0.05 mm.

It should also be mentioned with regard to the sealing membrane that itpreferably consists of a material with a certain hardness, which can bein the range of 20-100 Shore-A, 50 85 Shore-A, 40 90 Shore D or 60 80Shore-D on the Shore scale according to DIN EN ISO 868 and DIN ISO7619-1, for example.

The sealing element (e.g. sealing membrane) can be manufactured withinthe scope of the disclosure by various manufacturing processes. Forexample, subtractive manufacturing processes such as milling, drillingor laser processing are suitable for manufacturing the sealing element(e.g. sealing membrane). Alternatively, it is possible to use additivemanufacturing processes such as 3D printing, laser sintering or lasermelting. Other possible manufacturing processes are injection moulding,deep drawing and vacuum melting.

In one embodiment of the disclosure, the sealing membrane has severalmembrane layers, which makes leakage detection possible. Between theindividual membrane layers of the sealing membrane, a leakage borepreferably opens out of the print head in order to detect a leakage whenone of the membrane layers has become permeable. The second membranelayer then provides additional security. For example, the leakage borecan be connected to a sensor which then detects the leakage due to acoating agent escaping from the leakage bore. Alternatively, it is alsopossible for the leakage bore to lead into a sight glass or atransparent hose in order to detect a leakage optically. The leakagebore can then also lead into a dirt diluent disposal or into acollecting tray or into a collecting groove.

In one embodiment of the disclosure, the sealing membrane has no holesfor the valve needles to pass through. This is advantageous because theholes can otherwise cause sealing problems. With this design of thesealing membrane without holes, the sealing membrane can have a shapednozzle closure tip on the nozzle side to open or close the respectivenozzle or the upstream valve seat depending on the deflection of thesealing membrane. The sealing membrane thus not only fulfils thefunction of a seal, but also forms the nozzle closure tip. Theindividual valve needles can each be firmly connected to the sealingmembrane, so that a displacement of one of the valve needles leads to acorresponding deflection of the sealing membrane with the nozzle closuretip formed on it.

In a different embodiment of the disclosure, however, the sealingmembrane has a hole for each individual valve needle. The individualvalve needles can be passed through the corresponding hole in thesealing membrane, whereby the individual valve needles are firmly andfluid-tightly connected to the sealing membrane. On the one hand, theindividual holes in the sealing membrane are sealed against the valveneedles to prevent the passage of liquid through the holes. On the otherhand, the connection between the valve needles and the sealing membranemay also cause a displacement of the individual valve needles to lead toa corresponding deflection of the sealing membrane.

In a different embodiment of the disclosure, on the other hand, a nozzleclosure tip is inserted in each of the individual holes of the sealingmembrane on the side of the nozzle chamber, which optionally opens orcloses the associated nozzle depending on the deflection of the sealingmembrane. The valve needles, on the other hand, are firmly connected tothe sealing membrane in the area of the holes, in particular by a screwconnection between the valve needles on the one hand and the nozzleclosure tip on the other, which are arranged on opposite sides of thesealing membrane.

In one embodiment of the disclosure, the valve needles each have a valveneedle tip that tapers conically towards its free end.

In addition, the disclosure allows the individual valve needle tips toeach have a separate sealing element.

For example, the separate sealing element can be glued onto the valveneedle tip. Alternatively, it is also possible for the valve needle tipto have a socket in which the valve needle tip is inserted.Alternatively, it is also possible for the valve needle tip to beenclosed by the separate sealing element over part of its length.

It should also be mentioned that the valve needle and the sealingelement can be made of different materials, in particular metal for thevalve needle and plastic for the sealing element.

The sealing element can be attached to the tip of the valve needle byinjection moulding, dipping, welding or vulcanising, to name just a fewexamples.

It has already been briefly mentioned above that the sealing membranecan have several membrane layers, which makes leakage detectionpossible. Alternatively, however, it is also possible that not a singlesealing membrane with several membrane layers is used, but severalseparate membranes which enclose a fluid space between them. Onemembrane is arranged on the nozzle side and encloses the nozzle chamber,which is filled with the coating agent to be applied during operation.The other membrane, on the other hand, is arranged on the actuator sideso that the two membranes enclose a fluid space between each other. Thisalso enables leakage detection and has further design advantages, asexplained in detail below.

The applicator according to the disclosure preferably has a coatingagent inlet in order to feed the coating agent to be applied into thenozzle chamber of the applicator. In addition, the applicator accordingto the disclosure preferably has a coating agent outlet in order todischarge non-applied coating agent from the nozzle chamber, for examplewithin the scope of a material circulation. Furthermore, the applicatoraccording to the disclosure preferably has a barrier fluid inlet inorder to introduce a barrier fluid into the fluid space between the twomembranes. Finally, the applicator according to the disclosurepreferably also has a barrier fluid outlet to discharge the barrierfluid from the fluid space between the two membranes, for example withinthe framework of a material circulation.

In addition, the disclosure also claims protection for an applicationsystem with the above described applicator according to the disclosureand other parts or components.

Thus, the application system according to the disclosure preferablycomprises a source of coating agent which feeds the coating agent intothe coating agent inlet of the applicator. The coating source mayinclude, for example, a coating tank, pump and valves.

In addition, the application system according to the disclosurepreferably also includes a barrier fluid source which feeds the barrierfluid into the barrier fluid inlet of the applicator. The barrier fluidsource may include, for example, a fluid reservoir, pump and valves.

A throttle may be connected to the barrier fluid outlet of the inventedapplicator to affect the pressure of the barrier fluid in the fluidspace.

In addition, a controllable coating agent valve may be connected to thecoating outlet of the invented applicator. For example, the coatingagent valve can direct the coating agent exiting the applicator to awaste container for disposal or to a circulation container for reuse.

In addition, a controllable barrier fluid valve may be connected to thebarrier fluid outlet of the invented applicator. The barrier fluid valvecan direct the escaping barrier fluid, for example, to a waste containerfor disposal or to the barrier fluid source for reuse.

The barrier fluid may be a liquid such as a water-based detergent, anorganic detergent or a solvent mixture. Alternatively, the barrier fluidmay be a gas, such as compressed air. Other variants, on the other hand,provide that the barrier fluid is a paint component of the paint to beapplied or a paint compatible medium, such as (C10-C21)alkanesulfonicacid phenyl ester (Mesamoll®).

The application system according to the disclosure preferably also has acontrol device which controls the filling of the fluid chamber and/orthe nozzle chamber with the barrier fluid or with the coating agent tobe applied.

For example, the control device can fill the fluid chamber with thebarrier fluid in a time-controlled manner, for example hourly, daily,weekly or monthly.

Alternatively, it is possible for the control unit to fill the fluidchamber once with the barrier fluid before the start of the application.

Alternatively, it is also possible for the barrier fluid to flowpermanently through the fluid chamber.

During operation of the application system according to the disclosure,it is preferably intended that the barrier fluid source fills the fluidspace of the applicator with a certain pressure of the barrier fluid.

For example, the pressure of the barrier fluid in the fluid space can beopen-loop-controlled, i.e. without a feedback loop.

Alternatively, it is also possible to control the pressure of thebarrier fluid in the fluid space using a control loop, i.e. a feedbackloop. For example, the coating agent pressure in the nozzle chamber orthe barrier fluid pressure in the fluid chamber can be measured by apressure sensor and the pressure can then be controlled by a pressureregulator at the coating agent inlet and/or outlet.

In an alternative to the disclosure, the predetermined pressure of thebarrier fluid in the fluid chamber is greater than the coating agentpressure in the nozzle chamber, in particular by 0.5 bar, 1 bar, 2 baror 3 bar higher. The result of this pressure difference is that thepressure difference on both membrane sides pushes the membrane on thenozzle side in the direction of the nozzles, so that this membranebiases the valve needles in the direction of a closed position.

Another alternative, however, provides that the predetermined pressureof the barrier fluid in the fluid chamber is less than the coating agentpressure in the nozzle chamber, especially by 0.5 bar, 1 bar, 2 bar or 3bar. The membrane on the nozzle side is thus deflected in the directionof the actuators by the pressure difference between the two membranesides, so that this membrane biases the corresponding valve needles intoan open position.

In another alternative, however, it is provided that the predeterminedpressure of the barrier fluid in the fluid space is essentially equal tothe coating agent pressure in the nozzle chamber. In this alternative,the pressure of the barrier fluid in the fluid space thus compensatesthe coating agent pressure in the nozzle chamber, so that the actuatorsdo not have to overcome any pressure-related force, but only theinherent elasticity of the membrane.

Furthermore, the application system can have an expansion vessel, anexpansion membrane or a piston cylinder to influence the pressure of thebarrier fluid in the fluid space of the applicator.

It has already been mentioned above that the multiple membranes allowleakage detection. The application system according to the disclosuretherefore preferably includes a pressure sensor which enables thepressure of the barrier fluid in the fluid space to be measured in orderto allow leakage detection.

It has also been briefly mentioned above that the pressure of thebarrier fluid in the fluid space exerts a counterforce on the nozzleside membrane to compensate, amplify or overcompensate for the pressureof the coating agent on this membrane. It should be noted that the valveneedles are preferably fixed or at least frictionally connected to thesealing membrane, so that a displacement of the valve needles results ina corresponding deflection of the sealing membrane, while a deflectionof the sealing membrane results in a corresponding deflection of thevalve needles. The sealing membrane and the valve needles take eachother with them. The coating agent pressure in the nozzle chamberpresses from one side against the sealing membrane and thus generates acorresponding opening force on the valve needles, which pushes the valveneedles into an open position. The barrier fluid pressure in the fluidchamber, on the other hand, presses in the opposite direction on thesealing membrane and thus generates a closing force which acts on thevalve needles. For example, the closing force can be higher or lower andalso substantially equal to the opening force.

Finally, the disclosure also includes the idea of introducing a shock ofcompressed air into the nozzle chamber. A compressed air source can beprovided for this purpose, which introduces the compressed air shockinto the nozzle chamber, especially after assembly of the applicationsystem and before filling the applicator with the coating agent to beapplied. This idea has its own importance worthy of protection andtherefore enjoys protection independently of the other aspects of thedisclosure, i.e. even without the features of the main claim.

Furthermore, the disclosure also includes a corresponding operatingprocedure for the disclosure-appropriate applicator or thedisclosure-appropriate application system. The individual process stepsof the operating procedure conforming to the disclosure are described inthe above description of the applicator or application system conformingto the disclosure, so that reference is made to the above description toavoid repetitions.

FIGS. 1A and 1B show various schematic representations of a print headaccording to the disclosure that can be used in a paint shop to applypaint to vehicle body components. In some respects, the design andfunction of the print head according to the disclosure corresponds tothe known print heads described above, so that only the detailsessential to the disclosure are described in more detail below.

The print head according to the disclosure initially has a nozzle plate1 with numerous nozzles 2-5, whereby a spatially narrowly limited jet ofcoating agent can be emitted through each of the nozzles 2-5. Only thefour nozzles 2-5 are shown in this schematic representation. In fact,however, the print head according to the disclosure has a considerablylarger number of nozzles, which can be arranged in rows and columns, forexample, which is not apparent from this schematic representation.

The individual nozzles 2-5 are each assigned a valve needle 6-9, wherebythe individual valve needles 6-9 are each movable in the direction ofthe double arrow.

To move the individual valve needles 6-9, several electromagneticactuators 10-13 are provided, which here are only schematically drawn asa coil.

The valve needles 6-9 can optionally close or release the nozzles 2-5depending on their position. In the representation shown in FIG. 1A, allnozzles 2-5 are closed by the corresponding valve needles 6-9 so that nopaint is released. In the representation shown in FIG. 1B, however, thevalve needle 7 is lifted from nozzle 3 so that a spray of paint or adrop is emitted through nozzle 3, as indicated by the arrow. In the FIG.1B the other nozzles 2, 4, 5 are closed by the corresponding needles 6,8 or 9.

In addition, the print head according to the disclosure has a continuoussealing membrane 14, which fluidically separates a nozzle chamber 15from an actuator chamber 16 in the print head. The coating to be appliedis led via the nozzle chamber 15 to the individual nozzles 2-5, i.e. thenozzle chamber 15 is filled with the coating to be applied duringoperation.

In the actuator chamber 16, on the other hand, there are the actuators10-13 or only the valve needles. The sealing membrane 14 prevents paintfrom the nozzle chamber 15 from penetrating into the actuator chamber16. This is advantageous because the heating of the actuators 10-13 doesnot affect the paint at all or only to a negligible extent, thuspreventing heat-induced paint buildup in the nozzle chamber 15 and inthe actuator chamber 16. In addition, the separation by the sealingmembrane allows 14 colour changes, since the actuator chamber 16 doesnot have to be rinsed.

It should be mentioned here that the individual valve needles 6-9 caneach be passed through holes in the sealing membrane 14, whereby thesealing membrane 14 can be firmly connected to the individual valveneedles 6-9. As a result, for example, the displacement of the valveneedle 7 in FIG. 1B leads to a corresponding local deflection of thesealing membrane 14. This local deflection of the sealing membrane inthe area of the valve needle 7 also leads to corresponding forces on theadjacent valve needles 6 and 8 due to the elasticity of the sealingmembrane 14. However, the sealing membrane 14 is designed in such a waythat an undesired interaction between the adjacent valve needles 6 onthe one hand and 8 on the other hand is prevented. This is important sothat the individual valve needles 6-9 can be opened and closedindependently of each other. The sealing membrane 14 therefore has athree-dimensional structure that prevents the deflection of the sealingmembrane from leading to mechanical crosstalk with the adjacent valveneedles 6 or 8. This three-dimensional structure will be described indetail later.

FIGS. 2-4 show various possible designs for the passage, connection orplacement of the valve needles 6-9 through the sealing membrane 14,whereby the drawings only show the valve needle 6.

In FIG. 2, the valve needle 6 is continuous and thus forms a sealingelement at the same time with its nozzle closure tip 17 for closing orreleasing a corresponding valve seat.

In addition, it can be seen from the drawing that a sealing collar 18 isintegrally formed on the sealing membrane 14, which protrudes from thesealing membrane 14 both towards the actuator chamber 16 and towards thenozzle chamber 15.

In the design as shown in FIG. 3, the nozzle closure tip 17 is separatedfrom the valve needle 6 and screwed to the valve needle 6. The sealingmembrane 14 is pressed between the valve needle 6 and the nozzle closuretip 17 so that the valve needle 6 is firmly connected to the sealingmembrane 14. A displacement of the valve needle 6 thus leads to acorresponding deflection of the sealing membrane 14.

In the design shown in FIG. 4, the sealing membrane 14 does not have ahole for the valve needle 6 to pass through. Rather, the nozzle closuretip 17 is integrally formed onto the sealing membrane 14. Here, too, thevalve needle 6 is firmly connected to the sealing membrane 14, so that adisplacement of the valve needle 6 leads to a corresponding deflectionof the sealing membrane 14.

FIG. 5 shows a sealing membrane 14 with integrally formed nozzle closuretips. The valve needle 6 can be connected to the sealing membrane 14,but it can also only be fitted. In the case of a valve needle 6 onlyattached, the opening of the nozzle is caused by the paint pressure. Thepaint pressure deforms the sealing membrane 14 in the direction of theactuator chamber 16 away from the nozzle chamber 15.

FIG. 6 shows a schematic representation of a sealing membrane 14 inconformity with the disclosure, which partly corresponds to theembodiments described above, so that reference is made to the abovedescription to avoid repetition, using the same reference signs forcorresponding details.

It should be noted that numerous holes 20 are arranged equidistantly ina single linear row of holes 21 in the sealing membrane 14. The holes 20in the sealing membrane 14 are used to pass through the valve needles6-9 or the other valve needles not shown in the previous drawings, asdescribed above.

As a result of the structural elements 19, a local deflection of thesealing membrane 14 due to a corresponding displacement of theassociated valve needle 6 remains locally limited and does notmechanically transfer to the adjacent valve needle 7.

The structural elements 19 of the three-dimensional structure of thesealing membrane 14 are triangular in a view of the sealing membrane 14.It should also be mentioned that one row of the triangular structuralelements 19 is arranged on each side of the row of holes 21. Thus one ofthe triangular structural elements 19 is arranged on each side of theindividual holes 20. It should also be mentioned here that theindividual structural elements 19 taper from the inside to the outside,as can also be seen from the drawing.

The height of the individual structural elements 19 can be constant orincrease or decrease from the inside to the outside.

FIG. 7 shows a modification of FIG. 6, so that to avoid repetitions theabove description is referred to, for which the same reference signs areused for corresponding details.

A feature of this embodiment is that the triangular structural elements19 are arranged between the adjacent holes 20 of the sealing membrane14. The holes 20 and the structural elements 19 are all located withinthe row of holes 21.

It should also be mentioned that the individual structural elements 19are aligned with their longitudinal axis parallel to the row of holes21.

FIGS. 8A, 8C show a variation of the example shown in FIG. 6, so that toavoid repetition, reference is made to the above description, using thesame reference marks for appropriate details.

A feature of this example is that the triangular structural elements 19extend from the inside to the outside.

Another feature of this example is that the height of the triangularstructural elements 19 increases from the inside to the outside, as canbe seen in FIG. 8B.

FIGS. 9A, 9C show a further variation, which is also largely consistentwith the embodiments described above, so that reference is made to theabove description to avoid repetitions, using the same reference signsfor corresponding details.

A feature of this example is that the three dimensional structuralelements 19 are shaped as ribs.

It should also be mentioned that the three-dimensional structuralelements 19 formed as ribs can have a constant height, as can be seenfrom the comparison of FIGS. 9B and 9C. However, they may also have anoutwardly rising or falling height.

FIGS. 10A, 10E show a further variation, which in turn is largelyconsistent with the above examples of execution, so that to avoidrepetition, reference is made again to the above description, using thesame reference signs for the corresponding details.

A feature of this embodiment is that the three-dimensional structure ofthe sealing membrane comprises 14 different types of structural elements19A, 19B. The structural elements 19A are recessions, while thestructural elements 19B are elevations.

However, the two structural elements 19A and 19B are also triangular andtaper in the sealing membrane 14 inwards towards the longitudinal axisof row of holes 21.

It should also be mentioned that the height of the structural elements19B decreases from the outside to the inside. Similarly, the depth ofstructural elements 19A increases from the inside to the outside, asshown in FIG. 10E and FIG. 10D.

FIGS. 11A-11E show a variation of the design according to FIGS. 10A,10E, so that in order to avoid repetitions, reference is made again tothe above description, using the same reference signs for correspondingdetails.

A feature of this example is that the structural elements 19A, which arerealized as recesses, are arranged on both sides of the holes 20,whereas the structural elements 19B, which are realized as elevations,are arranged between two adjacent holes 20 of the row of holes 21.

FIG. 12 shows a detail enlargement from FIG. 11A. The drawing shows adistance d1 between the adjacent holes. In addition, the drawing shows adistance d2 between the row of holes 21 and the edge of the sealingmembrane 14. Furthermore, the drawing shows a distance d3 between theadjacent structural elements 19A, 19B.

Preferably, the following dimensional ratios may apply:

-   -   d1/d3≥1;2;3;4 Essentially=1;2;3;4        -   d2/d1≥1;3;5;10

Finally, FIGS. 13 and 16 show 16 different possible designs of thesealing force 18.

In FIG. 13, the sealing collar 18 protrudes only in one direction fromthe sealing membrane 14, namely towards the actuator chamber 16.

In the design according to FIG. 14, the sealing collar 18 also onlyprotrudes in one direction from the sealing membrane 14, i.e. in thedirection of the nozzle chamber 15.

In the design according to FIG. 15, the sealing collar 18, on the otherhand, protrudes from the sealing membrane 14 in both directions.

Finally, FIG. 16 shows a sealing collar 18 with a triangularcross-section. This can point both in the direction of the actuatorchamber 16 and in the nozzle chamber 15.

FIG. 17 shows an application system according to the disclosure with anapplication head according to the disclosure, which partly correspondsto the above described embodiments. In order to avoid repetitions,reference is therefore made to the above description, where the samereference signs are used for the corresponding details.

A feature of the applicator in this embodiment is that two sealingmembranes 14 a and 14 b are provided.

The sealing membrane 14 a is arranged on the nozzle side and essentiallycorresponds to the sealing membrane 14 in the previous examples. Thesealing membrane 14 a thus encloses the nozzle chamber 15.

In contrast, the second sealing membrane 14 b is arranged on theactuator side and encloses a fluid space 22 together with thenozzle-side sealing membrane 14 a.

To introduce the paint to be applied into the applicator, the applicatorhas a coating agent inlet 23.

In addition, the applicator has a coating agent outlet 24, wherebyunapplied coating agent can be discharged from the applicator, forexample in the course of material circulation.

Furthermore, the applicator has a barrier fluid inlet 25 for introducinga barrier fluid (e.g. compressed air, water-based rinsing agent, organicsolvent) into the fluid space 22.

The barrier fluid can then exit the applicator through a barrier fluidoutlet 26.

The paint to be applied is taken from a paint container 27 and fed intothe coating agent inlet 23 of the applicator by means of a pump 28. Thesupplied paint then leaves the applicator either via the nozzles 2-5 orwithin the framework of a material circulation through the coating agentoutlet 24.

A controllable valve 29 is connected to the coating agent outlet 24,whereby the valve 29 directs the emerging coating agent either into awaste container 30 or back into the paint container 27 within the scopeof a material circulation.

The barrier fluid is taken from a barrier fluid source 31 and fed via apump 32 into the barrier fluid inlet 25 of the applicator.

The barrier fluid then leaves the applicator via the barrier fluidoutlet 26 to a pressure sensor 33, which measures the barrier fluidpressure in the fluid space 22 and thereby enables leakage detection.

The escaping barrier fluid is then directed by a controllable valve 34either into the waste container 30 or back to the barrier fluid source31 within the framework of a material circulation.

FIGS. 18A and 18B show different pressure ratios in the nozzle chamber15 on one side and in the fluid space 22 on the other side.

Thus the barrier fluid pressure p_(s) in the fluid space 22 in FIG. 18Ais equal to the coating agent pressure p_(m) in the nozzle chamber 15.This means that the barrier fluid pressure p_(s) in the fluid space 22compensates the coating agent pressure p_(m) in the nozzle chamber 15,so that no pressure-related forces act on the sealing membrane 14 a.

In the condition shown in FIG. 18B, the barrier fluid pressure p_(s) inthe fluid space 22 is greater than the coating agent pressure p_(m) inthe nozzle chamber 15. As a result, the pressure difference exerts adeflection force on the sealing membrane 14 a, which in turn biases thevalve needle 6 into a closed position, i.e. downwards in the drawing.

The disclosure is not limited to the preferred embodiments describedabove. Rather, a large number of variations and modifications arepossible which also make use of the disclosure idea and therefore fallwithin the scope of protection.

1.-23. (canceled)
 24. A system for applying a coating agent to acomponent, said system comprising: an applicator including a nozzlechamber having a plurality of nozzles for dispensing the coating agentin the form of continuous jets or droplets, the coating agent flowing inuse through the nozzle chamber to the nozzles so that the nozzle chamberis filled with the coating agent in use; a coating agent inlet forsupplying the coating agent to be applied into the nozzle chamber of theapplicator; a coating agent source which feeds the coating agent intothe coating agent inlet of the applicator; a plurality of displaceablevalve needles which are assigned to the individual nozzles andselectively open or close the respective nozzle as a function of theposition of the valve needle; an actuator chamber for accommodatingactuators for displacing the valve needles; and a sealing element, whichfluidically separates the actuator chamber from the nozzle chamber inorder to avoid contamination of the actuator chamber with the coatingagent in the nozzle chamber, the sealing element designed such that theindividual valve needles can be displaced independently of one anotherwithout a displacement of one of the valve needles affecting the openingand closing of the nozzles at the adjacent valve needle.
 25. The systemaccording to claim 24, wherein the sealing element between the nozzlechamber and the actuator chamber comprises at least two membranesenclosing a fluid space between them.
 26. The system according to claim25, further comprising a barrier fluid inlet for supplying a barrierfluid into the fluid space between the two membranes.
 27. The systemaccording to claim 26, further comprising a barrier fluid source whichfeeds the barrier fluid into the barrier fluid inlet of the applicator28. The system according to claim 27, wherein the barrier fluid sourcefills the fluid space of the applicator with a specific pressure of thebarrier fluid.
 29. The system according to claim 27, further comprisinga barrier fluid outlet for returning the barrier fluid from the fluidspace of the applicator to a barrier fluid return.
 30. The systemaccording to claim 29, further comprising a throttle at the barrierfluid outlet for influencing the pressure in the fluid space.
 31. Thesystem according to claim 29, further comprising a barrier fluid valveat the barrier fluid outlet, the barrier fluid valve directing theunapplied barrier fluid from the applicator selectively to a wastecontainer for disposal or to the barrier fluid source for reuse.
 32. Thesystem according to claim 26, wherein the barrier fluid is one of thefollowing fluids: a) a liquid, b) a gas, c) one component of the paintto be applied, d) a paint compatible medium.
 33. The system according toclaim 26, wherein a) a control device is provided for controlling thefilling of the fluid space of the applicator with the barrier fluid, andb) the control device fills the fluid space once with the barrier fluidin each case before the start of application, and c) the control devicefills the fluid space in a time-controlled manner.
 34. The systemaccording to claim 26, wherein the pressure of the barrier fluid in thefluid space is adjusted in an open-loop-controlled manner without afeedback loop.
 35. The system according to claim 26, wherein thepressure of the barrier fluid is controlled by a control circuit. 36.The system according to claim 26, wherein the predetermined pressure ofthe barrier fluid in the fluid space is greater than the coating agentpressure in the nozzle chamber.
 37. The system according to claim 26,wherein the predetermined pressure of the barrier fluid in the fluidspace is smaller than the coating agent pressure in the nozzle chamber.38. The system according to claim 26, wherein the predetermined pressureof the barrier fluid in the fluid space is substantially equal to thecoating agent pressure in the nozzle chamber.
 39. The system accordingto claim 26, further comprising: a) an expansion vessel, an expansionmembrane or a piston cylinder for adjusting the pressure of the barrierfluid in the fluid space of the applicator, and b) a pressure sensor formeasuring the pressure of the barrier fluid in the fluid space to enableleakage detection.
 40. The system according to claim 26, wherein a) thevalve needles are firmly or frictionally connected to the nozzle-sidemembrane, so that a displacement of the valve needles leads to acorresponding deflection of the nozzle-side membrane, while a deflectionof the nozzle-side membrane leads vice versa to a correspondingdeflection of the valve needles, and b) the coating agent pressure inthe nozzle chamber acts on the nozzle-side membrane and the nozzle-sidemembrane thereby exerts an opening force on the valve needles, theopening force pressing the valve needles in the direction of an openposition, so that the actuators must overcome the opening force when thevalve needles are displaced into a closed position, and c) the barrierfluid pressure in the fluid space acts against the coating agentpressure in the nozzle chamber on the nozzle-side membrane and thenozzle-side membrane thereby exerts a closing force on the valveneedles, the closing force pressing the valve needle in the direction ofthe closed position, and d) the closing force is greater than theopening force than the opening force.
 41. The system according to claim24, further comprising a compressed air source for introducing acompressed air shock into the nozzle chamber.
 42. The system accordingto claim 24, further comprising a coating agent outlet for returning thenon-applied coating agent from the nozzle chamber of the applicator to acoating agent return.
 43. The system according to claim 42, furthercomprising a coating agent valve at the coating agent outlet, thecoating agent valve directing the unapplied coating agent from theapplicator selectively to a waste container for disposal or to thecoating agent source for reuse.